Magazine feed of sample with thermal isolation of sample from ionization chamber



March 4, 1969 c. BRUNNE E ET AL 3,431,451

MAGAZINE FEED OF SAMPLE WITH THERMAL ISOLATION OF SAMPLE FROM IONIZATION CHAMBER Filed July 27. 1965 Sheet of z Fig1 mun/mes cuer BIFU/WVFE GOA/TE)? MPH/3 March 4, 1969 c. BRUNNE E ET AL 3,431,451

MAGAZINE FEED OF SAMPLE WITH THERMAL ISOLATION OF SAMPLE FROM IONIZATION CHAMBER Filed July 27, 1965 Sheet 2 of 2 Fig.2

Q 3 A 2b A F l L L N 4b 2a 5 I7 6 2o 15 21 I4 1L 1 MI i i i m 5 cuer BKU/WVFE O N 61/11/751? KAPPU'S BY'MW /////Afi United States Patent ()flice 3,431,451 Patented Mar. 4, 1969 MAGAZINE FEED F SA MPLE WITH THERMAL ISOLATION OF SAMPLE FROM IONIZATION CHAMBER Curt Brunne, Bremen, and Giinter Kappus, Bremen- Huchting, Germany, assignors to Varian mat G.m.b.H., Bremen, Germany, a limited company of Germany Filed July 27, 1965, Ser. No. 475,068

Claims priority, application (zlgrmany, July 30, 1964,

vs. Cl. 313-231 Claims rm. Cl. H013 17/26, 61/28, 61/52 ABSTRACT OF THE DISCLOSURE The present invention relates to an apparatus for investigation of material by vaporisation, ionisation and ion current measurement.

The present invention is based on the observation that for a reliable measurement it is essential that the vaporisation of the substance to be investigated takes place in the immediate vicinity of the ionisation chamber, but on the other hand, mutual thermal influences between the ion sources and the vaporising device should be avoided as far as possible. It is an object of the invention to provide an apparatus for the solution of this problem, wherein for the substance to be investigated, a vaporisation cell is provided which is arranged directly adjacent the ionisation chamber or the ionising electron beam and which is open towards the ionisation chamber but is thermally isolated, the cell having a window which is open towards the ionisation chamber,

Furthermore, in order to keep the impurities in the vaporisation cell as low as possible, it is important that when changing the samples in the vaporisation cell, only the substance to be investigated, with a carrier therefor, is introduced. For this purpose, a crucible which is open towards the cell window which faces the ionisation chamber can be provided as the carrier for the material.

In order to achieve as low as possible a spacing of the vaporisation source from the ionisation chamber, the ionisation box can be provided with an indentation which receives the vaporisation cell.

The thermal insulation of the vaporisation cell can be achieved by means of a cooling and heating system, which allows the vaporisation cell to be kept at the optimum temperature suited to the material to be investigated, independently of the temperature of the ionisation chamber. In order to be able to selectively heat or cool, the vaporisation cell may be provided with a cooling jacket in which a heating coil is disposed.

Advantageously, attached to the vaporisation cell is a channel with a magazine for a series of samples slidable therein. Thus, one side of the transverse channel can be arranged as a supply chamber for receiving the entire magazine, and provided with an opening which can be closed in a vacuum-tight manner, for charging and discharging the magazine, whereas the supply chamber can be closed in a vacuum-tight manner relative to the supply channel, by a piston provided at one end of the magazine. For exchanging the magazine samples, advantageously a slide is provided in the supply channel.

The above and other objects and advantages of the invention will be apparent from the following description taken with reference to the accompanying drawings, which are given by way of example and in which:

FIG. 1 diagrammatically illustrates a mass spectrometer for analysis purposes, provided with an ion source and test sample introduction arrangement; and

FIG. 2 illustrates the ion source and sample introduction arrangement to a larger scale than FIG. 1 and partly in section.

In a vacuum chamber 1, an ionisation box 2 is provided which is machined out of the solid, and in which by electron bombardment in the region of an electron beam A generated in known manner, within an ionisation chamber 3, the material to be investigated and which passes into the chamber in the form of vapour, is ionised. The ions which are formed are drawn in known manner from the ionisation box 2 by electric fields perpendicularly to the plane of the drawing, that is to say forwardly, and either entirely or as shown in FIG. 1 after focusing and mass spectrometric separation of the ion bundle B in the sector field of an electromagnet M by alteration of the magnetic field strength or of their acceleration before entry into the field of the separating magnet M, are separated according to their mass numbers and passed through an exit gap Sp to an ion intercepter F, and qualitatively and quantitatively measured or mass spectrographically recorded by a current measuring device S (see FIG. 1).

For vaporising the fluid or solid substance to be investigated, this is introduced into the vaporising cell 4. This vaporising cell is arranged laterally relative to the electron beam A, within a depression 5 of the ionisation box 2. This depression is formed by a correspondingly cylindrically constricted or milled-out side wall 2a of the ionisation box 2. The vaporisation cell 4 is not bodily connected with the ionisation source 2, in order to achieve a high quality thermal insulation. For the purpose of this thermal separation, that is to say independent temperature formation in the vaporisation cell 4 and in the ionisation box 2, the vaporisation chamber 4a of the cell 4 is surrounded by a cooling water jacket 6 and in the vaporisation chamber 4a an electric heating coil 7 is arranged which is connected to a suitable source of electrical energy, just as the water jacket 6 is connected to a source of cooling water which is not shown in the drawing.

The vaporisation chamber 4a, into which the sample is introduced, is open towards the electron beam A in the ionisation box 2, and for this purpose is provided with a window 4b which is disposed in front of the sample and which is opposite a corresponding window 2b in the wall 2a of the ionisation box.

The sample to be vaporised is introduced in a vessel 8, for example of glass, into the cell in such a manner that the vessel opening faces the window 4b. The vessel 8 is pushed into an electric heating coil 8a and its temperature is measured by a thermo-element 8b, both of which are held by a stationary holder 8c. For introduction of the sample, the vaporisation cell is connected to a channel 9 which is intersected by a transverse channel 10 with a magazine 11 for a series of samples in separate vessels 8, slidable therein.

The right hand side of the transverse channel 10 is arranged as the supply chamber 10a for receiving the entire magazine 11, and is provided with a cover 13 which can close the chamber 10a in a vacuum-tight manner.

The magazine with the vessels 8 can be pushed by means of a piston 14 with a shank 15, transversely to the supply channel 9, so that in each case one of the vessels 8 passes into the region of a plunger 16 for being pushed out of the magazine into the vaporisation cell 4. The plunger 16 magnetically holds the vessel 8 which is pushed out of the magazine 11. For this purpose, magnets 17 are fixed on the bottoms of the vessels. During the mass spectrometric measurement, the plunger 16 remains in the advanced position and returns the vessel into the magazine where it is retained by abutment on the bottom of its mount 11a, and thus separated from the plunger 16 which continues its return movement, so that after corresponding displacement of the magazine the plunger can move another vessel from the magazine into the vaporisation cell.

The valve piston 14 closes the supply chamber 10a in a vacuum-tight manner relative to the supply channel 9. It is however possible to vent the supply chamber for the purpose of changing the magazine, without impairing the vacuum in the supply channel and in the vaporisation chamber. For re-evacuating the supply chamber 10a, a preliminary vacuum pump or high vacuum pump 19 can be connected to the same through a valve 18.

The magazine 11 is detachably connected to the piston 14, so that it can be replaced or removed after opening of the cover 13, and refilled. The piston 14 is connected with the shank 15 in such a manner that it is non-rotatable in a neck portion of the housing but is longitudinally displaceably guided and can be adjusted at the outside of the neck portion, for example with the aid of a nut which is mounted on the threaded neck portion of the housing and which rotatably engages the shank 15 for effecting longitudinal movement thereof. The vacuum-tight closure of the transition opening for the shank is effected by a bellows 21 which surrounds the shank 15 and the ends of which are fixedly connected respectively to the piston 14 and the housing neck portion 20.

The plunger 16 is surrounded in a vacuum-tight manner by a housing portion 22 of non-magnetic material and can be moved by means of an axially displaceable magnet 24 which acts on an iron piece 16a provided on the end of the plunger.

Many modifications and other embodiments are possible within the scope of the invention. More particularly, the arrangement of a magazine in a supply chamber which can be closed relative to the vaporisation chamber, can be used without restriction to a particular kind of vaporisation device.

We claim:

1. Apparatus for investigating material by vaporisation comprising,

chamber means defining an ionisation chamber having a source of an electron beam for bombarding ions introduced therein,

said chamber means being formed with a recess for accommodating a vaporisation cell and an inlet for receiving vapor from said vaporisation cell,

said vaporisation cell being formed with an outlet closely adjacent to said inlet and being thermally isolated from said chamber means by means including an insulating gap,

said inlet being located in said chamber means so as to define a short path between said outlet and said electron beam,

thermal means for controlling the temperature of said vaporisation cell,

and channel means defining a channel communicating with said vaporisation cell for receiving samples of material to be vaporized in said vaporisation cell to produce a vapor that is transmitted through said outlet and said inlet into said ionisation chamber for bombardment by said electron beam.

2. Apparatus for investigating material in accordance with claim 1 wherein said thermal means comprises means surrounding said vaporisation cell for both injecting heat into and withdrawing heat from said vaporisation cell.

3. Apparatus in accordance with claim 2 wherein said means surrounding comprises a heating coil and a liquid jacket for carrying coolant.

4. Apparatus in accordance with claim 1 wherein said channel means comprises a first channel transverse to a second channel,

said first channel intercoupling said vaporisation cell and said second channel,

said second channel having magazine means for carrying a series of samples in separate vessels slidable therein.

5. Apparatus in accordance with claim 4 wherein said second channel is formed with means defining a supply chamber for receiving said magazine means and further comprising,

cover means for closing said supply chamber substantially vacuum-tight.

6. Apparatus in accordance with claim 5 and further comprising,

piston means in said second channel for both closing said supply chamber vacuum-tight and moving said magazine means from said supply chamber toward said first channel.

7. Apparatus in accordance with claim 4 and further comprising plunger means for selectively moving said vessels from said magazine means into said vaporisation cell.

8. Apparatus in accordance with claim 5 and further comprising plunger means for selectively moving said vessels from said magazine means into said vaporisation cell.

9. Apparatus inaccordance with claim 6 and further comprising plunger means for selectively moving said vessels from said magazine means into said vaporisation cell.

10. Apparatus in accordance with claim 6 wherein said piston means comprises means for supporting said magazine means.

References Cited UNITED STATES PATENTS 2,690,515 9/1954 Mack 3 l323l X 2,703,843 3/1955 Cameron 2504l.9 2,756,341 7/1956 White 25()4l.9 3,158,740 11/1964 Craig et a1. 250-4l.9

JAMES W. LAWRENCE, Primary Examiner.

E. R. LAROCHE, Assistant Examiner.

US. Cl. X.R. 

